274 



BUU^TIN OF THE BUREAU OF FISHERIES. 



distinguished from other haliplids by the fact that the terminal joint of the labial 



palps is much shorter than the preceding joint, while the coxae of the hind legs 



cover only the first three segments of the abdomen and the fourth tarsal segment 



is much shorter than the first. 



Haliplus ruficollis (DeGeer). 



Dytiscus ruficollis (DeGeer, 1774, p. 204; pi. 16, fig. 9). 



Haliplus immaculicollis (Harris, 1828, p. 164). 



Haliplus ruficollis (Schi^dte, 1864, p. 161; pi. 8, figs. 1-12). 



Haliplus ruficollis (Matheson, 1912, p. 169 and 186; fig. C, text; pi. 13, figs. 22 and 24; pi. 14, figs. 32 and 36). 



The eggs. — The female cuta a hole with her mandibles in the side of a filament of Nitella and de- 

 posits several eggs within the algal cell, which hatch within 10 or 12 days. 



Habits of the larva. — This larva also crawls about slowly over the algae and can not run or swim. 

 It feeds exclusively upon algse, and for this purpose seizes the algal filament in its modified fore legs 

 and passes it backward until it finds a broken end. It then punctures the wall of the filament with 

 its mandibles and sucks out the fluid contents through the mandibular tubes. This larva has no tracheo- 

 lated spines for breathing, but spiracles are present on the last two thoracic and the first seven abdomi- 

 nal segments. Aeration is apparently accomplished in some way through these. 



Description of the larva. — Body very long and slender, made up of a head, three thoracic segments, 

 and 10 abdominal segments. Head short, depressed, narrower than the thorax. The three thoracic 

 and the first six abdominal segments about the same width, the seventh and eighth segments slightly 

 narrowed, the ninth half the width of the eighth, and the tenth less than half the width of the ninth. 

 This last segment is much prolonged and ends in two long spines, which are not jointed; the spines 

 end in long setae. The first seven abdominal segments are each armed with two dorsal plates, the eighth 

 and ninth with a single plate, all closely set with short spines. 



The antennae are four-jointed, the last joint made up of two longitudinal parts side by side, the 

 outer one terminated by a short spine. The mandibles are short and highly chitioized; each ends 

 in a curved hollow point or tip, which opens on its inner margin into a tube that runs to the base of the 

 mandible and there opens into the mouth. The maxillae approach those of the adult much more closely 

 tiian in any other beetle here described. The cardo is distinct and pyriform, the stipes very broad 

 with a row of setae along the outer margin and two large spines at the inner distal comer. At the outer 

 distal comer is home the palpifer and the three-jointed palp, the two basal joints of which are equal 

 and half the length of the terminal one, each with a seta on the outer margin. Along the terminal 

 margin is home the galea, which is broad, bluntly rounded and well armed with setae and spines. The 

 labium is narrow and elongate and is tipped with a row of long spines; the palps are two-jointed, the 

 terminal joint considerably longer than the basal, and both joints unarmed. 



The front legs are transformed from locomotor into grasping organs for the purpose of seizing and 

 handling the algal filaments upon which the larva feeds. In these legs the penultimate segment has 

 a process on the inner distal corner which extends outward beside the last segment and reaches the 

 tip of the latter. This process carries a spine on either side and two spines at the tip, between which 

 the terminal claw of the last joint shuts down. The process and the last joint together form a sort of 

 chela, guarded by the spines and the terminal claw, and form an admirable organ for handling fila- 

 mentous algae. 



Pupation. — Matheson (1912) found the eggs of this species and reared the larvae up to the point 

 where they began to enter the soil for pupation, but unfortunately was compelled to give up the work 

 before any larva actually transformed. Schi^dte (1864) described in detail the larva of this beetle 

 but said nothing about the pupa, and it remains still unknown. We may safely say, however, that 

 pupation takes place within an earthen chamber formed by the larva in much the same way as that 

 of the Peltodytes larva. 



Description of the pupa. — The pupa of this species is unknown, but Schi0dte obtained the pupa of 

 Haliplus variegatus, and from it we may obtain a good idea of the pupae of the genus. It showed the 

 same turning forward of the two front pairs of legs, with the knees projecting on either side of the head, 

 but they are not armed with spines in Schi0dte's figure. In place of the long curved styli on the pro- 

 notum of Peltodytes we find two short triangular spines at each anterior comer and two others on either 

 side of the mid line, with a row of four along the posterior margin. The mesonotum and metanotum each 



